Propagating Trees and Shrubs

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Trees and Shrubs can be raised from freshly collected or commercially obtained seed.

Different species may require different treatment to help them overcome dormancy.

For example, hard coated seed, may need the coating softened or chipped to allow germination to take place, others may require stratification.

Method:

To soften:

Place seed in a container, boil a kettle of water and allow the boiled water to go just go off the boil then pour it over the seed.

Allow the water to cool, repeat this process twice more or until the seed sinks.

Seeds Soaking

To chip:

Cut a nick in the seed coat with a knife.

Alternatively scarify it by rubbing it with a file or sandpaper.

Nicking a Seed

This allows moisture to quickly penetrate the seed as opposed to the lengthy natural softening period in the soil.

Sow immediately after either treatment.

To Stratify :

Some species require a period of warm stratification, others may require cold stratification, and some species require both.

The aforementioned treatments are generally carried out indoors by means of heaters and refrigerators.

Whereas an alternative method is to try and replicate what happens naturally in the wild, where seeds fall to the ground then are subjected to hot/cold stratification by means of the summer / winter weather.

Warm Stratification:

Place seed in a clear plastic bag filled with a moist, open-textured mix of peat or composted bark mixed with coarse sand or perlite.

Seal the bag and keep it at 18°-24 ° C (65°-75 ° F) for up to 12 weeks, before subjecting it to a period of cold stratification.

Cold Stratification:

This is carried out as follows;

Place seed in a clear plastic bag filled with a moist, open-textured mix of peat or composted bark mixed with coarse sand or perlite.

Place bag in a refrigerator,(not a freezer) keeping it below 5 °C (40°F) for about 12 weeks depending on the species.

Shake the bag periodically, and sow seed immediately it has germinated.

Natural, fluctuating cold is more effective, so leaving seeds outdoors is generally more successful than keeping in a refrigerator.

Naturural simulation:

The timing of this method is subject to when you obtain your seed.

For example,

Commercial seed can be sown around Week 13-15 or as per instruction on the packaging, whereas collected seed should be sown immediately after collecting when they are fresh.

Method:

Sow seed into 70mm (3”) pots of gritty potting compost.

Cover compost with a 6-12mm (¼”-½”) of agricultural grit.

Place these in a cold frame or similar cool, well-ventilated environment where excess rainfall cannot soak the pots.

Germination can be sporadic even with the best treatment, so leave the pots for up to two years if necessary.

Prick out seedlings into separate pots and grow on, planting them into a nursery bed once they are large enough.